Multi-touch manipulation of application objects

ABSTRACT

The manipulation system described herein provides a common platform and application-programming interface (API) for applications to communicate with various multi-touch hardware devices, and facilitates the interpretation of multi-touch input as one or more manipulations. Manipulations map more directly to user intentions than do individual touch inputs and add support for basic transformation of objects using multiple touch contacts. An application can use manipulations to support rotating, resizing, and translating multiple objects at the same time. The manipulation system outputs two-dimensional (2D) affine transforms that contain rotation, scale, and translation information. Thus, using the manipulation system the application author can focus more on building touch-capable applications and let the manipulation system handle the underlying transformations and communication with the multi-touch hardware.

RELATED APPLICATIONS

This application is a Continuation of U.S. patent application Ser. No.13/919,873 (allowed), filed Jun. 17, 2013, which is a Continuation ofU.S. patent application Ser. No. 12/258,437, (now U.S. Pat. No.8,466,879) filed Oct. 26, 2008, the disclosures of which areincorporated herein by reference in their originally filed form.

BACKGROUND

A tablet PC, or pen computer, is a notebook or slate-shaped mobilecomputer, equipped with a touch screen or graphics tablet/screen hybridtechnology that allows the user to operate the computer with a stylus,digital pen, or fingertip instead of a keyboard or mouse. Tablet PCsoffer a more natural form of input, as sketching and handwriting are amuch more familiar form of input than a keyboard and mouse, especiallyfor people who are new to computers. Tablet PCs can also be moreaccessible because those who are physically unable to type can utilizethe additional features of a tablet PC to be able to interact with theelectronic world.

Multi-touch (or multitouch) denotes a set of interaction techniques thatallow computer users to control graphical applications using multiplefingers or input devices (e.g., stylus). Multi-touch implementationsusually include touch hardware (e.g., a screen, table, wall, and so on)and software that recognizes multiple simultaneous touch points.Multi-touch stands in contrast to traditional touch screens (e.g.,computer touchpad, ATM, shopping kiosk) that only recognize one touchpoint at a time. Multi-touch hardware can sense touches using heat,finger pressure, high capture rate cameras, infrared light, opticcapture, tuned electromagnetic induction, ultrasonic receivers,transducer microphones, laser rangefinders, shadow capture, and othermechanisms. Many applications for multi-touch interfaces exist andapplication designers and users are proposing even more. Some uses areindividualistic (e.g., Microsoft Surface, Apple iPhone, HTC Diamond). Asa new input method, multi-touch offers the potential for new userexperience paradigms.

An application cannot use multi-touch hardware without an interface forthe application software to receive information from the multi-touchhardware. Unfortunately, each multi-touch hardware device includes itsown proprietary interface and application authors must have specificknowledge of a hardware device to write software that works with thedevice. For example, a multi-touch hardware provider may provide akernel-mode driver and a user-mode application interface through whichuser-mode software applications can communicate with the multi-touchhardware to receive touch information. An application author writessoftware that communicates with the user-mode application interface, butthe application author's software works only with that multi-touchhardware. A computer user with a different multi-touch hardware devicecannot use the application author's software unless the applicationauthor produces a different version of the software that operatescorrectly with the computer user's device. This produces a very limitedpotential market for application authors, reduces the incentive to writeapplications supporting multi-touch interactions, and keeps the cost ofthe most popular devices high for which the greatest number ofapplications is available.

Another problem is the difficulty for applications to determine a user'sintentions based on touch input received from multi-touch hardware.Touch input may be received as a list of coordinates where the hardwaresenses touch input at any given time. Each application has to includesoftware to interpret the coordinates and determine the user'sintention. For example, if an application receives information about twodifferent touches, a first touch at one position then later a secondtouch at a new position, it is up to the application to determinewhether the user used one finger for the first touch and another for thesecond touch, or whether the user slid the same finger from one locationto another location to produce the first touch and the second touch.Depending on the purpose of the application, these two differentinterpretations of the user input can have very different meanings.

SUMMARY

The manipulation system described herein provides a common platform andapplication-programming interface (API) for applications to communicatewith various multi-touch hardware devices, and facilitates theinterpretation of multi-touch input as one or more manipulations.Manipulations map more directly to user intentions than do individualtouch inputs and add support for basic transformation of objects usingmultiple touch contacts. An application can use manipulations to supportrotating, resizing, and translating multiple objects at the same time.The manipulation system outputs two-dimensional (2D) affine transformsthat contain rotation, scale, and translation information. Thus, usingthe manipulation system the application author can focus more onbuilding touch-capable applications and let the manipulation systemhandle the underlying transformations and communication with themulti-touch hardware.

This Summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This Summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used to limit the scope of the claimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram that illustrates components of themanipulation system, in one embodiment.

FIG. 2 is a data flow diagram that illustrates a typical operatingenvironment of the manipulation and the flow of data between components,in one embodiment.

FIG. 3 is a display diagram that illustrates an application objectmanipulated by touch input, in one embodiment.

FIG. 4 is a flow diagram that illustrates the input loop processing of amulti-touch application using the manipulation system, in oneembodiment.

FIG. 5 is a flow diagram that illustrates the processing of themanipulation system when the system receives touch input, in oneembodiment.

DETAILED DESCRIPTION

The manipulation system provides a common platform and API forapplications to communicate with various multi-touch hardware devices,and facilitates the interpretation of multi-touch input as one or moremanipulations. Manipulations map more directly to user intentions thando individual touch inputs and add support for basic transformation ofobjects using multiple touch contacts. For example, an applicationauthor receiving manipulations from the manipulation system candifferentiate a user sliding a finger from one location to another froma user setting down two different fingers without performing additionalinterpretation of the input. Manipulations provide support for multiplesimultaneous interactions. An application can use manipulations tosupport rotating, resizing, and translating multiple objects (e.g.,photos) at the same time. Unlike typical window-based user interfaces,there are no notions of focus or activation tying the user to a singleinput at a time. In addition, applications can retrieve manipulationinformation. The manipulation system outputs 2D affine transforms thatcontain rotation, scale (e.g., zoom), and translation (e.g., pan)information.

A contact is an individual touch of the multi-touch hardware. Forexample, when a user sets his/her finger on the multi-touch hardware,moves his/her finger around, and lifts his/her finger, that series ofevents is a single contact. The system identifies each contact with acontact identifier. A contact keeps the same identifier for as long asit exists. As the user moves various contacts around, the systeminterprets the movement as one or more manipulations. For example, ifthe user moves two contacts closer together or further apart, the systemmay determine that the user is scaling (e.g., zooming into or out from)an object. As another example, if the user moves multiple contacts in acircular motion, then the system may interpret the movement as arotation of an object. Each application can define objects that arerelevant differently, so it is up to the application to attach aninstance of the system (called a manipulation processor) to each objectthat a user can manipulate using touch input within the application. Forexample, a photo browsing application may attach a manipulationprocessor to each displayed photo, so that the user can move the photosaround, scale the photos, rotate the photos, and so forth. Thus, theapplication author can focus more on building touch-capable applicationsand let the manipulation system handle the underlying transformationsand communication with the multi-touch hardware.

FIG. 1 is a block diagram that illustrates components of themanipulation system, in one embodiment. The manipulation system 100includes a hardware interface 110, one or more manipulation processors120, a contact manager 130, an input transformation component 140, andan application interface 150. Each of these components is described infurther detail herein.

The hardware interface 110 communicates with the hardware to receivetouch contacts and movements. The hardware interface 110 may includeseveral subcomponents that work together to provide touch inputinformation. For example, the operating system may provide a commondriver model for multi-touch hardware manufacturers to provide touchinformation for their particular hardware. The operating system maytranslate touch information received through this model into windowmessages (e.g., WM_TOUCH described herein) and pass these messages tothe application. Thus, the hardware interface 110 may involve thecoordination of the hardware, a hardware driver, and an operating systemlayer. The result is a series of messages to the manipulation systemthat identify a particular contact (e.g., touch of a finger), and thecoordinates of the contact over time. For example, the operating systemmay provide a message when a new contact is set down on the multi-touchhardware, a message each time the contact moves, and a message when auser lifts the contact away from the multi-touch hardware.

One or more manipulation processors 120 use the input transformationcomponent 140 to interpret movement of each contact associated with aparticular application object. The manipulation processor 120 maydetermine that a user is using multiple contacts to perform a singleaction. For example, a user could touch a photo with all five fingers ofone hand and twist his/her hand to indicate an intention to rotate thephoto. The manipulation processor 120 receives five separate contacts(one for each finger) and the change in coordinates of each contact asthe user rotates his/her hand. The manipulation processor 120 determinesthat each contact is grabbing the same object and performing the samerotation. The system will inform the application that the user rotatedthe object, but the application can ignore whether the user used two,five, or any particular number of fingers or other contacts to performthe rotation. This greatly simplifies the authoring of the applicationbecause the application author can handle those types of manipulationsthat are relevant to the application and leave it to the manipulationsystem to interpret the meaning of each low-level touch input receivedfrom the multi-touch hardware.

Each manipulation processor 120 manages a list of contacts associatedwith the manipulation processor, and stores velocity vector andtranslation information about the contacts as the manipulation processor120 receives new low-level touch information. The contact manager 130represents the part of the system 100 that handles contact managementfor manipulation processors 120. It is up to the application to informthe manipulation system which contacts should be associated with eachmanipulation processor. The application can make this determination whenthe application receives low-level touch information, for example, byhit testing application objects using coordinates associated with thereceived low-level touch information. For example, if a user placesthree fingers on the same photo in a photo editing application, theapplication determines that the contact associated with each finger istouching the same object, and associates each of the three contacts withthe same manipulation processor. The contact manager 130 manages thelist of associated contacts on behalf of the manipulation processor 120and tracks the movement of the contacts to interpret manipulations ofthe associated object intended by the user.

The manipulation processor 120 uses the input transformation component140 to make determinations about the meaning of received movements ofvarious contacts, both alone and in concert. For example, if a user ismanipulating a photo with two fingers, which creates two correspondinginput contacts, then the manipulation processor 120 uses the inputtransformation component 140 to determine the meaning of relativemovements between the two contacts. If the two contacts move apart, thenthe input transformation component 140 may determine that the user isscaling the object to change the object's size. If the two contactsrotate, then the input transformation component 140 may determine thatthe user is rotating the object. If the two contacts both slide in aparticular direction, then the input transformation component 140 maydetermine the user is panning the object to a new location. Althougheach type of movement is described separately herein, a user can makeall three types of movements at the same time, and the inputtransformation processor can report the overall transformation to theapplication. For example, a user can rotate, scale, and pan an objectall in one motion.

The application interface 150 communicates with the application toreceive information and provide manipulation transforms to theapplication. The application interface 150 receives initializationinformation from the application. The initialization information mayspecify which types of transforms the application object supports for aparticular object and associated manipulation processor. For example,some application objects may support scaling but not rotation. Theinitialization information may also specify a pivot point of the object.The manipulation system provides manipulation transforms to theapplication through the application interface. For example, when themanipulation system receives low-level touch input that the systeminterprets as a recognized transform (e.g., a rotation), the systemfires an event to notify the application about the manipulation. Theapplication processes the manipulation transform to modify the objectbased on the transform. For example, if the user rotated the object,then the application may store the new orientation of the object to usethe next time the application displays the object.

The computing device on which the system is implemented may include acentral processing unit, memory, input devices (e.g., keyboard andpointing devices), output devices (e.g., display devices), and storagedevices (e.g., disk drives). The memory and storage devices arecomputer-readable media that may be encoded with computer-executableinstructions that implement the system, which means a computer-readablemedium that contains the instructions. In addition, the data structuresand message structures may be stored or transmitted via a datatransmission medium, such as a signal on a communication link. Variouscommunication links may be used, such as the Internet, a local areanetwork, a wide area network, a point-to-point dial-up connection, acell phone network, and so on.

Embodiments of the system may be implemented in various operatingenvironments that include personal computers, server computers, handheldor laptop devices, multiprocessor systems, microprocessor-based systems,programmable consumer electronics, digital cameras, network PCs,minicomputers, mainframe computers, distributed computing environmentsthat include any of the above systems or devices, and so on. Thecomputer systems may be cell phones, personal digital assistants, smartphones, personal computers, programmable consumer electronics, digitalcameras, and so on.

The system may be described in the general context ofcomputer-executable instructions, such as program modules, executed byone or more computers or other devices. Generally, program modulesinclude routines, programs, objects, components, data structures, and soon that perform particular tasks or implement particular abstract datatypes. Typically, the functionality of the program modules may becombined or distributed as desired in various embodiments.

FIG. 2 is a data flow diagram that illustrates a typical operatingenvironment of the manipulation system and the flow of data betweencomponents, in one embodiment. A multi-touch hardware device producesinputs 210 through a hardware interface. For example, the hardware maysend the inputs 210 to an operating system through a software driverprovided by the hardware manufacturer. The hardware interface providesinput events 220 to an application 230. For example, an application mayinform the operating system that the application 230 supportsmulti-touch user input and register to receive messages related tomulti-touch user input. The application 230 receives low-level touchinput information as input changes 240 and forwards the input changes240 to the manipulation system 250 described herein. For example, theinput changes 240 may describe each movement of one or more touchcontacts with the hardware using a set of coordinates that indicate eachcontact's current position and other movement characteristics. Themanipulation system 250 interprets the input changes 240 and notifiesthe application 230 of one or more manipulation events 260 that indicatehigher-level manipulations that the user is performing on a displayedobject. For example, if the movement of the contacts indicates that theuser intends to rotate the object, the manipulation events 260 indicatea degree of rotation.

Although the diagram illustrates that the application first receivestouch input and passes the touch input to the manipulation system, insome embodiments, the manipulation system receives touch input directlyfrom the hardware interface, interprets the touch input, and providesinterpreted manipulation events to the application. This represents analternative architecture that provides similar resultant functionalitybut gives the application less control over the processing of the input.For example, the application may not be able to define individualapplication objects to which the system attaches individual manipulationprocessors. The RTS plug-in described herein is one example of thisalternative architecture for the system.

FIG. 3 is a display diagram that illustrates an application objectmanipulated by touch input, in one embodiment. An application maysimultaneously display and receive touch input for many such objects.For example, the objects may represent one or more photographs stored onthe user's computer. The object 310 has a boundary 320 defined by theapplication based on the application's particular domain. For example, aphoto browsing application may have objects that represent user photosand the application may define the edge of each displayed photo as anobject boundary 320. A user touches the object with two initial contactsat locations 330 and 340. For example, the user may set his/her thumb atlocation 330 and index finger at location 340. Then, the user rotateshis/her fingers and moves them apart, such that the contacts end atlocations 350 and 360. The lines 370 and 380 illustrate the approximaterotation performed by the user's movement. The line 390 illustrates theapproximate stretching performed by the user's movement. Rather thanprovide the individual coordinates of the touch contacts 330-360, themanipulation system can indicate to the application the transformsperformed by the user, such as the degree of rotation and the scalefactor related to the stretching.

FIG. 4 is a flow diagram that illustrates the input loop processing of amulti-touch application using the manipulation system, in oneembodiment. In block 410, the application receives low-level touchinput. For example, an operating system or instance of the manipulationsystem receives touch contact information from multi-touch hardware andforwards the touch contact information to the application. In block 420,the application identifies the object to which the input applies. Forexample, the application may hit test the coordinates of the receivedinput by comparing the coordinates with the coordinates of eachapplication object displayed by the application. If the touch input iswithin the boundaries of a displayed application object, then theapplication determines that the touch input applies to that object. Inblock 430, the application sends the received touch input and theinformation about the identified application object to a manipulationAPI for invoking the manipulation system (see FIG. 5). For example, theapplication may create a numeric identifier for each application objectand pass the numeric identifier to the manipulation system each timetouch input corresponds to that object.

In block 440, the application receives a manipulation event from themanipulation system that describes one or more manipulations of theidentified application object. For example, the application may receivean event describing a 2D affine transform of the application object.Block 440 is illustrated serially after block 430 for simplicity ofillustration. In practice, the application may receive many touch inputevents before the manipulation system notifies the application with amanipulation event. There is not necessarily a one-to-one mapping oftouch input events to manipulation events. Because manipulation eventsrepresent a higher-level interpretation of low-level touch inputs,multiple touch inputs may make up a single manipulation event. In block450, the application handles the received manipulation event. Forexample, if the received manipulation event is a rotation, then theapplication may rotate the application object on the screen and storethe application objects new location for use when the applicationdisplays the application object again. The manipulation system frees theapplication from performing steps specific to a particular multi-touchhardware device or even from knowing which hardware device is providingthe multi-touch input. In addition, the manipulation system frees theapplication from processing individual contact movement and allows theapplication to focus on processing transforms at the application objectlevel.

In block 460, the application waits for the next touch input. Forexample, the application may call an operating system provided messageAPI, such as GetMessage on Microsoft Windows that waits for the nextmessage to be delivered to the application's message queue. In decisionblock 470, if the application receives the next touch input, then theapplication loops to block 410 to process the input, else theapplication loops to block 460 to continue waiting for further input.When the application closes, the application exits the input loop (notshown).

FIG. 5 is a flow diagram that illustrates the processing of themanipulation system when the system receives touch input, in oneembodiment. In block 505, the system receives touch input along withinformation identifying an application object with which the touch inputis associated. For example, the touch input may include coordinates orother location information of one or more touch contacts, and theapplication object information may include an identifier that theapplication assigned to a particular displayed object that the touchinput is over on the multi-touch hardware. In block 510, the systemidentifies a manipulation processor associated with the applicationobject. In decision block 520, if the system has not previouslyassociated a manipulation processor with the application object, thenthe system continues at block 530, else the system continues at block540. In block 530, the system creates a manipulation processor andassociates it with the application object, then continues at block 540.

In decision block 540, if the received touch input indicates that theapplication received a new contact (e.g., a touch down event), then thesystem continues at block 550, else the system continues at block 560.For example, a user may make initial contact of a finger with anon-screen object, or set down another finger (i.e., contact) on apreviously touched object. In block 550, the system adds the new contactto the list of contacts associated with the manipulation processor, andthen continues at block 560. In decision block 560, if the receivedtouch input indicates that the application received notification that atouch contact was removed (e.g., a touch up event), then the systemcontinues at block 570, else the system continues at block 580. Forexample, the user may lift one or more fingers from a previously touchedobject. In block 570, the system removes the contact from the list ofcontacts associated with the manipulation processor, and then continuesat block 580. In block 580, the system processes the touch input todetermine any manipulations represented by the touch input. For example,touch movement may indicate a rotation or translation manipulation,while touch contact removal may indicate completion of a manipulation.In block 590, the system fires a manipulation event to send transforminformation describing the manipulation to the application. For example,the system may provide a degree of angular rotation of the object to theapplication. After block 590, these steps conclude.

In some embodiments, the manipulation system is part of a message-basedoperating system, and the system receives messages related to touchinput that the operating system receives from the hardware. For example,using a paradigm similar to WM_MOUSEMOVE for mouse messages, futureversions of Microsoft Windows may provide a WM_TOUCH message thatcontains low-level touch movement information received from multi-touchhardware. The operating system may also provide finer grained messages,such as WM_TOUCHDOWN (when a new contact is made with the multi-touchhardware), WM_TOUCHMOVE (when an existing contact moves), and WM_TOUCHUP(when a contact is lifted from the multi-touch hardware). An applicationthat receives a WM_TOUCH-related message can invoke the manipulationsystem and pass the message to the manipulation system forinterpretation and processing. The application then receiveshigher-level events that represent the manipulation system'sinterpretation of the manipulation intended by the user based on thereceived low-level touch movement information.

In some embodiments, the manipulation system receives low-level touchmovement information from specialized hardware, such as a real-timestylus. For example, the Microsoft Tablet PC Software Development Kit(SDK) provides a real-time stylus (RTS) component that applicationauthors can extend with hooks. RTS hooks receive input from the RTShardware and can perform processing on the received input. Themanipulation system may provide a hook that an application can insertinto the RTS component to automatically process RTS and other input tomanipulate application objects as described herein. The RTS hookprovides a different way for the manipulation system to receive input,but the manipulation system interprets input and fires events to theapplication describing manipulations implied by the input as previouslydescribed. A user may use a combination of stylus and touch input. Forexample, the user may draw an object with the stylus and then rotate theobject using his/her fingers.

In some embodiments, a manipulation processor of the manipulation systemreceives initialization information from the application using thesystem. For example, an application may initialize the manipulationprocessor with information about the location of the center of anapplication object. This can allow the manipulation processor to betterinterpret a user's intentions from received low-level touch input. Forexample, if the user rotates a single touch contact in an arc around thecenter of the application object, the processor can treat the motion asa rotation manipulation. Without the initialization information, theprocessor may interpret the same movement as simply panning theapplication object in the arc that the touch contact moved. Thus, byproviding additional application context information to the manipulationprocessor, the application can allow the manipulation system to betterinterpret user manipulations.

In some embodiments, the manipulation system allows the application toreuse the same manipulation processor for the entire time that the useris manipulating a particular object. For example, the application mayrequest that the system create a manipulation processor for eachapplication object when the application starts and use that manipulationprocessor until the application closes. The application may also delaycreation of each manipulation processor until a user interacts with aparticular object using touch (e.g., when the application detects thefirst contact of an object). During the lifetime of a manipulationprocessor, contacts may come and go as the user lifts and touches themulti-touch hardware and performs various manipulations. Themanipulation processor tracks the list of current contacts and themanipulations represented by the movement of the contacts as describedherein.

In some embodiments, the manipulation system delays firing events to theapplication until the system has received an updated position for eachcontact associated with a particular manipulation processor or until acertain time has passed. If the system reacts too quickly, such asfiring events after each received contact update, then problems such asstuttering may occur. For example, if a user touches an applicationobject with two fingers and drags both fingers down the multi-touchhardware at the same time, it is likely that the system will receiveupdates for one contact slightly before updates for the other contact.If the system fires events for based on the contact updates as soon asthe system receives the updates, the system will report that the objectis rotating back and forth rapidly. If instead the system waits untilreceiving a new position for the second contact, or waits a period oftime (e.g., 100 milliseconds) to receive an update for the secondcontact, then the system can correctly differentiate a situation wherethe user is moving both contacts in the same direction and the updateswere received slightly apart in time from a situation where the user isin fact rotating the object by moving only one of the contacts. Thus,the system may perform this additional processing to provide asatisfactory user experience.

In some embodiments, the manipulation system is part of a common controlthat an application can invoke to provide a common user interface.Microsoft Windows provides common controls for displaying lists, trees,buttons, and so forth. Likewise, the manipulation system may provide amulti-touch based control for manipulating application objects in theways described herein. For example, the system may provide a scattercontrol that allows the user to display one or more objects andmanipulate the objects. The scatter control handles processing oflow-level touch input and associating the input with a particularapplication object, and the application receives events from the controlto handle the manipulations of the application objects. For example, ifthe control indicates that the user resized an object, then theapplication may store the objects new size.

In some embodiments, the manipulation system provides enhancedinterpretation of single touch contacts. For example, as previouslydescribed the system can interpret rotation of a single contact aroundthe center of an application object as a rotation rather than atranslation when the application initializes the manipulation processorwith the location of the center or other reference point (e.g., acorner) of the object. Similarly, the system can interpret other singletouch movements according to a predefined meaning. For example, thesystem may treat a user rotating a single contact in a circle around thecenter of an object as a manipulation to scale the object rather than arotation as would be literally implied by the user's movement.

In some embodiments, the manipulation system performs the processingdescribed herein in three dimensions. Although two-dimensionalmulti-touch hardware is described herein, those of ordinary skill in theart will recognize that the processing of the system described hereincan be applied equally well to three-dimensional (3D) manipulations ifhardware is available to provide coordinate movement in threedimensions. For example, hardware that detects pressure or uses camerasto detect 3D movement of a user's fingers could provide the coordinatesof movement in the third dimension to the manipulation system, and themanipulation system could then produce 3D transforms that describemanipulations (e.g., rotation, scaling, and translation) of objects inmultiple 3D directions.

The following table defines one API that the manipulation systemprovides to applications for processing multi-touch user input.

Properties: AutoTrack Indicates whether down events should be used toautomatically add input to the manipulation. PivotPointX Identifies thehorizontal center of the object. PivotPointY Identifies the verticalcenter of the object. PivotRadius Determines how much rotation is usedin single finger manipulation. SupportedManipulations Indicates whichmanipulations are supported by an object. Methods: HRESULTCompleteManipulation( ); Called when the developer chooses to end themanipulation. HRESULT GetAngularVelocity( Calculates the rotationalvelocity  [out] FLOAT* pAngularVelocity at which the target object ismoving. ); HRESULT GetExpansionVelocity( Calculates the rate at whichthe target  [out] FLOAT* pExpansionVelocity object is expanding. );HRESULT GetVelocityX( Calculates and returns the horizontal  [out]FLOAT* pX velocity for the target object. ); HRESULT GetVelocityY(Calculates and returns the vertical  [out] FLOAT* pY velocity. );HRESULT ProcessDown( Feeds data to the manipulation  MANIPULATION_IDprocessor associated with a target. manipulationId,  FLOAT x,  FLOAT y, DWORD timestamp ); HRESULT ProcessMove( Feeds data to the manipulation MANIPULATION_ID processor associated with a target. manipulationId, FLOAT x,  FLOAT y,  DWORD timestamp ); HRESULT ProcessUp( Feeds data tothe manipulation  MANIPULATION_ID processor associated with a target.manipulationId,  FLOAT x,  FLOAT y,  DWORD timestamp ); Events: HRESULTManipulationStarted( Handles the event when manipulation  [in] FLOAT x,begins.  [in] FLOAT y ); HRESULT ManipulationDelta( Handles events thathappen when a  [in] FLOAT x, manipulated object changes.  [in] FLOAT y, [in] FLOAT translationDeltaX,  [in] FLOAT translationDeltaY,  [in]FLOAT scaleDelta,  [in] FLOAT expansionDelta,  [in] FLOAT rotationDelta, [in] FLOAT cumulativeTranslationX,  [in] FLOAT cumulativeTranslationY, [in] FLOAT cumulativeScale,  [in] FLOAT cumulativeExpansion,  [in]FLOAT cumulativeRotation ); HRESULT ManipulationCompleted( Handles theevent when manipulation  [in] FLOAT x, finishes.  [in] FLOAT y,  [in]FLOAT cumulativeTranslationX,  [in] FLOAT cumulativeTranslationY,  [in]FLOAT cumulativeScale,  [in] FLOAT cumulativeExpansion,  [in] FLOATcumulativeRotation );

In the table above, MANIPULATION_ID is an identifier that theapplication assigns to each application object that a user canmanipulate. The application uses hit testing or other common methods todetermine to which object received touch input applies, looks up theidentifier associated with the object, and passes the identifier and thetouch input to the manipulation API for processing.

From the foregoing, it will be appreciated that specific embodiments ofthe manipulation system have been described herein for purposes ofillustration, but that various modifications may be made withoutdeviating from the spirit and scope of the invention. For example,although rotation, scaling, and translation manipulations have been usedas examples, other types of manipulations can be used with the systembased on any type of manipulation users want to perform with multi-touchhardware. Accordingly, the invention is not limited except as by theappended claims.

I/We claim:
 1. A computer-implemented method associated with generatinga manipulation event, the computer-implemented method comprising:receiving, from an application executing on a computing device having atouch-sensitive input surface, via a manipulation applicationprogramming interface, a plurality of touch inputs, the plurality oftouch inputs corresponding to a plurality of touches previously directedto the application; interpreting, after being received via themanipulation application programming interface, the received pluralityof touch inputs into at least one corresponding manipulation event, theat least one corresponding manipulation event representing at least onemanipulation based on relative movements of the plurality of touches onthe touch-sensitive input surface; and providing, via the manipulationapplication programming interface, the at least one correspondingmanipulation event to the application.
 2. The computer-implementedmethod of claim 1, wherein the at least one manipulation comprises atleast one manipulation of an object, the application being configured tomanipulate the object based on the provided at least one correspondingmanipulation event and to cause the manipulated object to be displayedby the computing device.
 3. The computer-implemented method of claim 1,wherein the plurality of touch inputs comprise two-dimensional inputpoints corresponding to the plurality of touches of the touch-sensitiveinput screen.
 4. The computer-implemented method of claim 1, wherein themanipulation application programming interface is configured to beinvoked by arbitrary applications executing on the computing device, theplurality of touch inputs being received from the application of thearbitrary applications that currently is invoking the manipulationapplication programming interface.
 5. The computer-implemented method ofclaim 1, wherein the at least one corresponding manipulation eventcomprises at least one geometric transform produced by an element thatreceived the plurality of touch inputs via the manipulation applicationprogramming interface.
 6. The computer-implemented method of claim 1,wherein the plurality of touch inputs comprises locations of the toucheson the touch-sensitive input surface.
 7. The computer-implemented methodof claim 6, wherein the plurality of touch inputs further comprisevalues corresponding to pressures applied by the plurality of touches onthe touch-sensitive input surface.
 8. The computer-implemented method ofclaim 1, wherein the at least one manipulation event comprises at leastone manipulation selected from the group consisting of a rotation event,a translation event, and a scaling event.
 9. The computer-implementedmethod of claim 2, wherein the at least one manipulation event comprisesat least one manipulation selected from the group consisting of arotation of the object, a translation of the object, and a scaling ofthe object.
 10. The computer-implemented method of claim 1, wherein theinterpreting comprises determining a meaning of a relative movementbetween a first touch of the plurality of touches and a second touch ofthe plurality of touches, wherein each type of relative movement betweenthe first touch and the second touch has a predetermined meaningassociated therewith.
 11. The computer-implemented method of claim 10,wherein the predetermined meaning is a meaning selected from the groupconsisting of a rotation of the object, a translation of the object, anda scaling of the object.
 12. The computer-implemented method of claim 1,wherein the interpreting comprises: tracking a movement of each touch ofthe plurality of touches; and determining the at least one correspondingmanipulation event based on the tracked movements.
 13. Thecomputer-implemented method of claim 12, wherein the at least onecorresponding manipulation event is an event selected from the groupconsisting of a rotation event, a translation event, and a scalingevent.
 14. The computer-implemented method of claim 2, wherein theinterpreting comprises: tracking a movement of each touch of theplurality of touches; and determining the at least one correspondingmanipulation event based on the tracked movements.
 15. Thecomputer-implemented method of claim 14, wherein the at least onemanipulation event comprises at least one manipulation selected from thegroup consisting of a rotation of the object, a translation of theobject, and a scaling of the object.
 16. The computer-implemented methodof claim 2, wherein the application is further configured to determinewhether the plurality of touches are located within a boundaryassociated with the object.
 17. A computing device comprising: atouch-sensitive input display; a processor and storage, that, when thecomputing device is operating, execute an application and implement amanipulation application programming interface, the processor receiving,from the application, via the manipulation application programminginterface, a plurality of touch inputs, the plurality of touch inputscorresponding to a plurality of touches of the touch-sensitive inputdisplay directed to the application; the processor, after receiving theplurality of touch inputs via the manipulation application programminginterface, interpreting the plurality of touch inputs into at least onecorresponding manipulation event, the at least one correspondingmanipulation event representing at least one manipulation based onrelative movements of the plurality of touches on the touch-sensitiveinput surface; and the application receiving, via the manipulationapplication programming interface, the at least one correspondingmanipulation event.
 18. The computing device of claim 17, wherein the atleast one manipulation comprises at least one manipulation of an object,the application being configured to manipulate the object based on theat least one manipulation event and to cause the object to be displayedby the touch-sensitive input display.
 19. The computing device of claim17, wherein the plurality of touch inputs comprise two-dimensional inputpoints corresponding to the plurality of touches of the touch-sensitiveinput screen.
 20. The computing device of claim 17, wherein themanipulation application programming interface is configured to beinvoked by arbitrary applications executing on the computing device, theplurality of touch inputs being received from the application of thearbitrary applications that currently is invoking the manipulationapplication programming interface.
 21. The computing device of claim 17,wherein the at least one manipulation event indicates at least onegeometric transform, the at least one manipulation event produced by anelement that received the plurality of touch inputs via the manipulationapplication programming interface.
 22. The computing device of claim 17,wherein the plurality of touch inputs comprises locations of the toucheson the touch-sensitive input surface.
 23. The computing device of claim22, wherein the plurality of touch inputs further comprises valuescorresponding to pressures applied by the plurality of touches on thetouch-sensitive input surface.
 24. The computing device of claim 17,wherein the at least one manipulation event comprises at least onemanipulation selected from the group consisting of a rotation event, atranslation event, and a scaling event.
 25. The computing device ofclaim 18, wherein the at least one manipulation event comprises at leastone manipulation selected from the group consisting of a rotation of theobject, a translation of the object, and a scaling of the object. 26.The computing device of claim 17, wherein the interpreting comprisesdetermining a meaning of a relative movement between a first touch ofthe plurality of touches and a second touch of the plurality of touches,wherein each type of relative movement between the first touch and thesecond touch has a predetermined meaning associated therewith.
 27. Thecomputing device of claim 26, wherein the predetermined meaning is ameaning selected from the group consisting of a rotation of the object,a translation of the object, and a scaling of the object.
 28. Thecomputing device of claim 17, wherein the processor performs theinterpreting by tracking a movement of each touch of the plurality oftouches, and by determining the at least one corresponding manipulationevent based on the tracked movements.
 29. The computing device of claim28, wherein the at least one corresponding manipulation event is anevent selected from the group consisting of a rotation event, atranslation event, and a scaling event.
 30. The computing device ofclaim 18, wherein the processor performs the interpreting by tracking amovement of each touch of the plurality of touches, and by determiningthe at least one corresponding manipulation event based on the trackedmovements.
 31. The computing device of claim 30, wherein the at leastone manipulation event comprises at least one manipulation selected fromthe group consisting of a rotation of the object, a translation of theobject, and a scaling of the object.
 32. A computing device comprising:a contact-sensitive input device; processing hardware and storagestoring information to enable the processing hardware, when thecomputing device is operating, to execute an operating system to executearbitrary applications and to provide an application programminginterface to the arbitrary applications; an application executed by theprocessing hardware when the computing device is operating; an objectexecuted by the processing hardware when the computing device isoperating, the object instantiated via the application programminginterface by an application executing on the computing device, theobject comprising interpretation logic, wherein the application passestouch inputs to the object, the touch inputs corresponding to touches ofthe contact-sensitive input device; the object, when the computingdevice is operating, applies the interpretation logic to interpret thetouch inputs to identify a manipulation operation indicated by the touchinputs; and the application, when the computing device is operating,receiving an indication of the manipulation operation, the indicationhaving been triggered by the object having identified the manipulationoperation.
 33. A computing device according to claim 32, wherein themanipulation operation comprises a geometric transform.
 34. A computingdevice according to claim 33, wherein the geometric transform comprisesa rotation transform, a translation transform, and/or a scalingtransform.
 35. A computing device according to claim 33, wherein theoperating system provides the touch inputs.
 36. A computing deviceaccording to claim 35, wherein the object generates an event to causethe application to receive the indication of the manipulation operation.37. A computing device according to claim 32, wherein the objectmaintains a history of touch inputs received by the object.
 38. Acomputer-implemented method associated with generating a manipulationevent, the computer-implemented method comprising: receiving, through anapplication executing on a computing device having a touch-sensitivedisplay, via an application programming interface, touch events, thetouch events corresponding to points of contact with the touch-sensitivedisplay; receiving the touch events from the application via theapplication programming interface, and in response interpreting thetouch events into a corresponding transformation event, thetransformation event representing at least one geometric transformationthat corresponds to relative movements of the points of contact with thetouch-sensitive input surface; and receiving, through the applicationprogramming interface, by the application, the at least onetransformation event.
 39. A computer-implemented method according toclaim 38, wherein the application receives the transformation event witha callback or an event handler.
 40. A computer-implemented methodaccording to claim 38, wherein the touch events are initiated by anoperating system of the computing device.
 41. One or morecomputer-readable storage hardware storing information that, whenexecuted by a computing device, cause the computing device to perform aprocess associated with generating a manipulation event, the processcomprising: receiving, from an application executing on a computingdevice having a touch-sensitive input surface, via a manipulationapplication programming interface, a plurality of touch inputs, theplurality of touch inputs corresponding to a plurality of touchespreviously directed to the application; interpreting, after beingreceived via the manipulation application programming interface, thereceived plurality of touch inputs into at least one correspondingmanipulation event, the at least one corresponding manipulation eventrepresenting at least one manipulation based on relative movements ofthe plurality of touches on the touch-sensitive input surface; andproviding, via the manipulation application programming interface, theat least one corresponding manipulation event to the application. 42.The computer-implemented method of claim 41, wherein the at least onemanipulation comprises at least one manipulation of an object, theapplication being configured to manipulate the object based on theprovided at least one corresponding manipulation event and to cause themanipulated object to be displayed by the computing device.
 43. Thecomputer-implemented method of claim 41, wherein the plurality of touchinputs comprise two-dimensional input points corresponding to theplurality of touches of the touch-sensitive input screen.
 44. Thecomputer-implemented method of claim 41, wherein the manipulationapplication programming interface is configured to be invoked byarbitrary applications executing on the computing device, the pluralityof touch inputs being received from the application of the arbitraryapplications that currently is invoking the manipulation applicationprogramming interface.
 45. The computer-implemented method of claim 41,wherein the at least one corresponding manipulation event comprises atleast one geometric transform produced by an element that received theplurality of touch inputs via the manipulation application programminginterface.
 46. The computer-implemented method of claim 41, wherein theplurality of touch inputs comprises locations of the touches on thetouch-sensitive input surface.
 47. The computer-implemented method ofclaim 46, wherein the plurality of touch inputs further comprise valuescorresponding to pressures applied by the plurality of touches on thetouch-sensitive input surface.
 48. The computer-implemented method ofclaim 41, wherein the at least one manipulation event comprises at leastone manipulation selected from the group consisting of a rotation event,a translation event, and a scaling event.
 49. The computer-implementedmethod of claim 42, wherein the at least one manipulation eventcomprises at least one manipulation selected from the group consistingof a rotation of the object, a translation of the object, and a scalingof the object.
 50. The computer-implemented method of claim 41, whereinthe interpreting comprises determining a meaning of a relative movementbetween a first touch of the plurality of touches and a second touch ofthe plurality of touches, wherein each type of relative movement betweenthe first touch and the second touch has a predetermined meaningassociated therewith.
 51. The computer-implemented method of claim 50,wherein the predetermined meaning is a meaning selected from the groupconsisting of a rotation of the object, a translation of the object, anda scaling of the object.
 52. The computer-implemented method of claim51, wherein the interpreting comprises: tracking a movement of eachtouch of the plurality of touches; and determining the at least onecorresponding manipulation event based on the tracked movements.
 53. Thecomputer-implemented method of claim 52, wherein the at least onecorresponding manipulation event is an event selected from the groupconsisting of a rotation event, a translation event, and a scalingevent.
 54. The computer-implemented method of claim 52, wherein theinterpreting comprises: tracking a movement of each touch of theplurality of touches; and determining the at least one correspondingmanipulation event based on the tracked movements.
 55. Thecomputer-implemented method of claim 54, wherein the at least onemanipulation event comprises at least one manipulation selected from thegroup consisting of a rotation of the object, a translation of theobject, and a scaling of the object.
 56. The computer-implemented methodof claim 52, wherein the application is further configured to determinewhether the plurality of touches are located within a boundaryassociated with the object.